In the related art, master slave type medical manipulators including a master manipulator manipulated by an operator and a slave manipulator that is operated on the basis of a signal issued from the master manipulator are known as medical manipulators. A surgical tool for performing treatment on a treatment target region through remote manipulation is attached to such a medical manipulator.
For example, a surgical tool having a double joint for changing the orientation of a treatment part at a distal end part of a longitudinal member is disclosed in U.S. Pat. No. 6,312,435. The double joint has two rotary shafts that extend in directions orthogonal to the longitudinal axis of the longitudinal member and are parallel to each other. One of the two rotary shafts is coupled to the longitudinal member, and the other of the two rotary shafts is coupled to the treatment part. Additionally, in the surgical tool described in U.S. patent application No. 6,312,435, the double joint is provided with a pair of openable and closable treatment tool pieces. As for the pair of treatment tool pieces provided at the surgical tool described in U.S. patent application No. 6,312,435, elongated driving members that independently operate the treatment tool pieces are connected to the treatment tool pieces, respectively.